Or, if the Sonic fandom's prevailing popular ships are any indication, you can ship the immortal 50-year-old with the titular 15-year-old.
I hate these people.
IMO using lore age as an indication of noncery is a bad idea. Nonces keep using that excuse that the visibly underage character is actually a 3000 year old dragon and there's nothing stopping someone from drawing the canonically 8 years old Tails as a 30 year old adult. The best way to judge it, if it looks like a child, it is a child. If it looks like an adult, it's an adult. What you see is what you get.


Would you be able to tell that one of these characters is 15 years old and the other is 50 years old just by the looks alone? No, they have the exact same body proportions.
Now, did CaptArgo favorited sexual art of Tails and Cream that
didn't make them look like children? No, therefore he is a nonce that is sexually aroused by fictional imagery of prepubescent children. Same with bestiality porn where animals are talking, the Harkness test is the same type of cop-out as the 3000 year old dragoness excuse.
Remember that with furry porn, no one cares about the lore. When people jack it to sexualized animatronics from FNAF, none of them think about the lore of dead children in those. Not the guy that made it or the guy that spanked the monkey to it. They see image, the neurons activate. It's that simple.